Wire-drawing.



UNITED STATES PATENT OFFICE.

BURNIE BENBOW, F CLEVELANIO, OHIO, ASSIGNOB TO GENERAL ELECTRIC COMPANY,A CORPORATION OF NEW YORK.

WIRE-DRAWING.

Specification of Letters Patent. Patented J an, 11, 1916.

Applicationfiled December 7, 1912. Serial No. 735,551.

No Drawing. To all whom it may concern: been dried out) which is madequite shiny Be it known that I, BURNIELEE BENBOW, a citizen of theUnited States, residing at Cleveland, county of Cuyahoga, State of Ohio,have invented certain new and useful Improvements in Wire-Drawing, ofwhich the following is a specification.

My invention relates to the art of wire drawing and the like, andparticularly to the lubrication of wire in its passage tions, the wiremay be drawn through a number of succeeding dies before this coatmgrequires to be renewed.

I have found that by a mode of dealing with the material employed forlubricating purposes different from that hitherto practised a degree oflubrication may be obtained without the baking operation above set forthby the first die. Under favorable cond1-' 35 centigrade or higher.

45 effected, for example,

50 gives a smooth,

through the drawing dies. I have hereinafter described my invention moreparticularly with reference to its application to the hot drawing ofmetals, since it is adaptable -with peculiar advantage to the specialconditions and difficulties of this mode of drawing. The invention is,moreover, of particular value in the hot drawing of tungsten wire forincandescent electric lamp filaments and for other purposes as describedin British Patents 23,499 of 1909 and 8031 of 1910, in United StatesPatent 1,022,182 granted April 2, 1912 to John T. H. Dempster, and inUnited States Patent No. 1,082,933,

granted December 30, 1913, to William D.

Coolidge, and I have hereinafter referred to the wire as tungsten wire.

As described in the above mentioned patents and application, thetungsten wire is drawn through a diamond die or other suitable' diewhile at a temperature which may vary from below incipient redness to abri ht red heat or higher, the die being also pre erably heated to atemperature of say 200 to 500 To lubricate the wire in its passagethrough the die, finely divided graphite carried by a vehicle such aswater or oil has been applied to it, and (as more particularly set forthin the Demp- 40'ster patent above mentioned) the graphite has been madeto adhere in a fairly even and more or less permanent coating by bakingit on the wire or burning it into the wire before the latter enters thedie,-this being by heating the wire to redness just prior to theapplication of the lubricant, or in a subsequent heating whereby thewireis brought to the drawing temperature. This bakin or burning operationblac adherent, graphitic lubricating coating (from which all the water,oil, or other liquid has, of course,

which while inferior to that resulting from this baking. operation ismuch superior to anything hitherto obtained without it. I have furtherfound that by the employment of a heating or baking operation in connection with this mode of dealing with the lubricating material it ispossible to secure a degree of lubrication superior to anything obtainedby baking as hitherto employed, and that the ease of drawing can beenhanced and the die-wear reduced quite materially. In particular, thecoating thus secured is more even and more adherent, and does not flakeor scale off in the heating flame as the coating previously obtained wasmore or less liable to'do, nor scrape off as much at the die entrance,and it is therefore much more effective both as a lubricant and inprotecting the tungsten wire from oxidation. This latter function of thecoating is, perhaps, as important as its direct lubricating action; forthe friction in the die of the tungsten oxids usually formed by theoxidation of the wire is very much greater than that of metallictungsten, and the die-Wear is, therefore, also greater when oxidation ofthe wire occurs.

According to my invention, the material employed for lubricatingpurposes or to protect the wire from oxidation is associated, in asolution or suspension or the like in any suitable liquid vehicle, withmaterial which will constitute or furnish a binder to make the fineparticles of such lubricating material or those by which the lubricationor protection is ultimately efi'ected stick or adhere to the wire. Ofcourse the character of the material thus employed for eitherlubricating or binding purposes will depend upon the character andproperties of the material employed for the other of these purposes, andalso upon whether the mode of procedure is such as to bring about anychemical or other change which will materially affect the roperties ofeither the lubricating or the Binding material. Thus, for example, ifthe lubrlcating liquid is applied and the wire drawn through the diewithout any heating of either the wire or the die, the.

binding material should ordinarily act as a binder from the very outset;while if a baking operation such as above described is emloyed, thebinding material should act as a inder before the baking or afterward orboth,-irrespective of any change that the baking may produce initsaccording to the action required in order that the lubricatingmaterial may stick to the wire evenly in the first place and adhere toit as it passes through the die. Chemical changes in the bindingmaterial such as may be causedfby heat are indeed, generally favorableto the adhesion which it is desired to roduce, and serve, as it were, tofix the inding material and the coating even better than heatunaccompanied by any such change.

While any materials and any solvent or vehicle liquid which meet theneeds of the case as above indicated and are not injurious to the wireor the die may be employed, for the hot drawing of tungsten carbonaceousmaterials are especially suitable, both on account of their action inreducing the oxids of tungsten and for other reasons. As binding agents,indeed, carbonaceous or organic. materials unite efiicacy before andafter heating or baking to an extent nearly if not position of thischaracter commerciallyknown as aqua-dag with 2% pints 'of water andadding either 70 cubic centimeters of the glucose solution marketedunder thename ofvKaro Kern syrup or the same amount of solution made byadding a minimum of water to cane sugar and boiling down to molasses,about one cubic centimeter of a 2 per cent. mercury bichlorid solutionor a proper amount of some other suitable preservative being preferablyadded to each .pint of the total mixture. It may be observed thatcommercial aqua-dag itself apears to contain organic matter designed tokeep in suspension the relatively coarser particles of graphite thatmight otherwise tend to settle out, and that such organic matter has insome slight degree a binding action similar to that of the glucose andthe cane sugar just mentioned. The amount of ove stated are be appliedto the wire by drawing the latter through a vessel containing the liquidor 'througha body of cotton waste to which. 7 V.

the llquidhas been apphed in excess, as de-,

scribed in the aforesaid-Dempster patent, or bypassing-the wire over adeep grooved revolving pulley partially immersed in a body of theliquid, asdescribed in the appllicatlon of James W. MacKenzie, Serial 0.722,000, filed in the United States Patent Ofiice, September 23, 1912,under the title Wire lubrication .and the like, and assigned to theassignee of this ap lication, or in any other suitable manner. hecoating thus formed will be found to adhere to the wire without anybaking or heating, especially if the liquid is got rid of by allowing itto dry before the wire enters the die. Superior results can, however, beobtained by heating the wire so as to firmly fix the coating as well asget rid of the liquid, and as it were, bake the residual coating on thewire in a. smooth, close, firmly adhesive 'condition-the very bestresults, indeed,

usually being secured when the binding material has been entirelycarbonized. The heating or baking may be accomplished by passing thewire to which the liquid lubricant has beenapplied through a zone of gasflame of suitable length to heat it to a bright red heat for toWhatever-temperature is preferred for the drawing operation, the wirepassing from the flame right into the die, or, for example,- in any ofthe other ways described in the above mentioned Dempster patent. y J

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is

1. A lubricant consisting of finely divided graphite in suspension and abinder composed of material which maybe carbonized by heating, theroportion of the said binder being considera ly'l'in'exc'ess of thatnecessary'to keep the said graphiteinsuspens1on.

2. A liquid lubricant comprising finely divided graphite in suspensionand a sugar syrup, the proportion of the latter being 7 considerably inexcess of that necessary to keep the graphite in suspension.

3. A lubricant consisting of deflocculated graphite and a bindertherefor composed of material which may be carbonized by heating, theproportion of the said binder being considerably in excess of thatnecessary to keep the said graphite in the deflocculated In witnesswhereof, Ihave hereunto set sta lteA 1 d 1 b d fl my hand this third dayof December, 1912;

lqui u ricant comprising e occulated graphite and a carbonizable syrup,the BURNIE LEE Q proportion of the latter being considerably Witnesses:in excess of that necessary to keep the HARRY J. Veer, graphite in thedefiocculated state. WILLIAM Enw. KOHN.

